"A semiconductor is like a raisin cake, where the raisins give the cake the special flavor that makes it sell. By itself, a semiconductor can't really conduct electricity that well, but if you introduce impurities into it then those impurities turn it into a conductor. The impurities are called dopants, and electric current travels through doped silicon under the right conditions. Think of the dopant atoms as the raisins in the raisin cake, and the raw semiconductor material that's in between the dopant atoms as the cake in which the raisins sit."